The Z80Processor class simulates the processor execution in a syncrhonous way. You start the execution with any of the available control methods and then wait until the method returns (see the execution stop conditions). There are two execution modes, depending on the control method you use to start execution.
This mode is initiated when the Start method or the Continue method of IZ80Processor is invoked. In this mode the processor just starts executing instructions in the order in which they are stored in memory, and does not stop until any of the execution stopping conditions applies. Control of the process is achieved by handling the memory access events and/or the instruction execution events.
The difference between Start and Continue is that the former does a processor reset prior to starting execution, while the later does not. A reset simply sets the PC, IFF1 and IFF2 registers, as well as the interrupt mode, to zero; and sets the AF and PC registers to FFFFh. There is also a separate Reset method that does the same without otherwise modifying the processor state.
HINT: To start execution at a memory address other than zero, you can invoke Reset, then manually set Registers.PC to the desired value, then invoke Continue.
Another way to get the processor started is to invoke the ExecuteNextInstruction method of IZ80Processor. This method will just execute the next instruction (as pointed by the PC register) and return. This may be useful for step-by-step debuggers.
The T states counters are appropriately updated in single instruction execution mode as they are in instruction execution loop mode (see the state properties). However the stop conditions do of course not apply in this mode.